1. Field of the Invention
This invention relates to a method of manufacturing a hydrocarbon conversion catalyst, and in particular to a method of manufacturing a hydrocarbon conversion catalyst which will exhibit an excellent effect as a fluid catalytic cracking catalyst to be used in a process of catalytically cracking a heavy oil containing 0.5 ppm or more in total of heavy metals such as nickel and vanadium, iron and copper, in particular at least nickel and vanadium for obtaining light oils such as gasoline and kerosene.
2. Prior Art
Conventionally the catalytic cracking of petroleum hydrocarbon has been conducted by contacting it with a catalyst so as to crack the petroleum hydrocarbon to obtain a large amount of light components such as LPG and gasoline, and a small amount of cracked light oils. The catalyst thus used is deposited thereon with coke, which is subsequently removed by burning it in air for reuse. In this case, a distillate such as light gas oil (LGO) and heavy gas oil HGO obtained from an atmospheric distillation column, or vacuum gas oil (VGO) obtained from a vacuum distillation column is mainly employed as a feed stock.
However, with recent trends that crude oils to be produced in the world are heavier oils, and that heavy oil is increasingly oversupplied due to a change in the balance of supply and demand of oils in the industry, it is also necessary to use heavy oils containing distillation residue, as one of the feed stocks.
Meanwhile, heavy oils containing distillation residue contain extremely a large amount of metals such as nickel, vanadium, iron, copper and sodium as compared with a distillate. These metals are known to deposit on a catalyst thereby extremely inhibiting the cracking activity and selectivity of the catalyst.
Namely, with an increase in the amount of these metals depositing on the catalyst, the cracking ratio of the feed stock is gradually decreased to such extent that a desired cracking ratio can no longer be attained, while extremely increasing the generation of hydrogen and coke, thus making the operation of the apparatus more difficult, and at the same time reducing the yield of desired liquid products.
The present inventors have found in the past that a catalyst comprising crystalline aluminosilicate zeolite and alumina-magnesia matrix can be used as a catalytic cracking catalyst having a high resistivity to metals (Japanese Patent Application Open-Gazette No. 59-150539). This catalyst can be manufactured by mixing alumina-magnesia hydrogel and zeolite, and then drying and calcining the mixture. The catalyst thus prepared is highly resistive to metals and can be suitably used for catalytically cracking a residual oil.
However, with this catalyst containing alumina-magnesia as a matrix, there is a tendency to inhibit the removal of aluminum from zeolite under a hydrothermal conditions, and in some cases it is difficult to obtain a product having an sufficient octane number for FCC (Fluid Catalytic Cracking Process) gasoline.
When an FCC catalyst is charged into FCC apparatus, the removal of aluminum from zeolite generally takes place in a regeneration column heated to a high temperature, thereby lowering the crystal lattice constant of the zeolite. As is generally recognized, there is an intimate correlation between the crystal lattice constant of the zeolite in the FCC catalyst and the octane number of gasoline thus produced. Namely, the smaller the crystal lattice constant of the zeolite, the higher the octane number of FCC gasoline is also much influenced by the nature of feed stock as well as by the operation conditions of an FCC apparatus.
Accordingly, even if a catalyst comprising alumina-magnesia as a matrix is employed, a gasoline having a desired octane number can be produced if a feed stock of high aromatic content is employed, or the cracking operation is conducted at a relatively high temperature. On the contrary, if a feed stock of high saturation is employed, or if the cracking operation is conducted at a relatively low temperature, a gasoline having an undesirable octane number may be produced.